The user interface of the OtoScreen IV is different from the OtoScreen III. Instead of a BOOST button that must be held down to engage the 40db tone, it has a 40db-Toggle button that switches the unit back and forth between the softer tone and the 40db tone.
Once the unit has been "toggled" to the 40db mode, it stays in this mode until "toggled" back to the softer sound level. In the 40dB mode you can test the patient for any frequency at the louder tone without sequencing through the softer tone first. This is convenient for testing adults and seniors when it is desireable to initially test at the louder 40db level. (Note - engaging the softer tone first is required with OtoScreen III)
As with the OtoScreen III device, a tone is only active when the SCAN button is pressed. See the User Manual for a more detailed explanation of the operation of the unit.
Holding the 40dB-Toggle button down turns the unit off (faster than the automatic shut off function of the unit).
There are two models available: Standard and Pediatric. The Standard model tests at 25db and 40db sound levels. The Pediatric model tests at 20 db and 40db sound levels. The switch plate color is light-brown for both models. The type of unit (Standard or Pediatric) is indicated by a sticker inside the unit.
Every unit is calibrated on precision equipment and comes with a calibration certificate. The acoustic calibration criteria are traceable to the National Institute of Standards and Technology (NIST) for sound intensity.